Sulphating aliphatic alcohols



Patented May 7, 1940 UNITED STATES SULPHATING ALIPHATIO ALCOHOLS 1 Max Engelmann, Wilmington, Del., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application August 27, 1938, Serial No. 227,063

3 Claims. (01. 260-459) This invention relates to a new method of sulphating unsaturated aliphatic alcohols containing 8 or more carbon atoms and more particularly to the sulphation of said alcohols with strong sulphating agents in the presence of a lower alkyl ester of an aliphatic monocarboxylic acid containfrom 1 to 8 carbon atoms.

This invention has as an object an improved method of sulphating unsaturated aliphatic alco- 10 hols whereby sulphation of unsaturated linkages is avoided. A further object is to employrelatively cheap diluents in the sulphation of unsaturated aliphatic alcohols which impart improved solubility, better physical appearance, and a desirable odor to the sulphation products. A still further object is to employ diluents in the sulphation reaction which do not need to be recovered and which increase the yields and purity of the sulphation products. Other objects will appear hereinafter.

These objects are accomplished by the following invention according to which unsaturated aliphatic alcohols containing 8 or more carbon atoms are sulphated in the presence of an alkyl ester 25 of an aliphatic monocarboxylic acid containing from 1 to 8 carbon atoms wherein the alkyl group in said ester contains from 1 to 8 carbon atoms.

The invention is illustrated, but not limited, by

720 parts of chlorosulphonic acid were dissolved in 604 parts of commercial ethyl acetate. 1220 parts of commercial oleyl alcohol were added over 35 a period of two hours at a temperature of to C. The sulphation mass was stirred one hour at -20 to 25 C. and then drowned in aqueous caustic soda solution. The product contained oleyl alcohol sulphated at the hydroxyl 40 group;

Any alkyl ester of an aliphatic monocarboxylic acid containing from 1 to 8 carbon atomswherein the alkyl group in said ester contains from 1 to 8 carbon atoms is a suitable diluent to employ 45 in the sulphation of an unsaturated aliphatic alcohol. In other words, the use of esters of aliphatic alcohols from methyl to octyl with carboxylic acids from formic to caprylic is contemplated. A high molecular weight ester may be used such as octyl acetate, butyl propionate, and ethyl caprylate. However, lower molecular weight esters such as methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, and propyl acetate are cheaper, and hence from an economic viewpoint they are more feasible to use.

In the sulphation of oleyl alcohol, it is preferable to employ ethyl acetate as. the diluent.

In place of chlorosulphonic acid, other strong sulphating agents may be used such as oleum, sul- 5 phuric monohydrate, bromosulphonic acid, and sodium chlorosulphonate. Chlorosulphonic acid is the preferred sulphating agent.

The temperature at which the reaction is run may be varied over wide limits, the optimum tem- 10 perature being dependent upon the nature of the unsaturatedaliphatic alcohol which is being sulphated. Thus, while temperatures of from to C. are preferred, lower and higher temperatures may beemployed in this reaction. 15

The method of carrying out the reaction with respect to the order of addition of the reagents also lends itself to several variations. The chlorosulphonic acid can be dissolved in the ester and added to the unsaturated aliphatic alcohol; 20 the unsaturated aliphatic alcohol can be added to a solution of chlorosulphonic acid in the ester, or the unsaturated aliphatic alcohol can be dis- ,solved in the ester and reacted with chlorosulphonic acid. t

Unsaturated alcohols which can be sulphated in accordance with the process described herein include oleyl alcohol, palmitoleyl alcohol, linoleyl alcohol, erucyl alcohol, undecenol, decenol, and octenol. I 80 It has been found that the presence of these esters exerts a profound influence upon the reaction, of chlorosulphonic acid upon unsaturated aliphatic alcohols. It is not clear just what is the mechanism of the reaction, but it is apparent 86 that the ester does not function as an inert diluent. When unsaturated alcohols, such as oleyl alcohol, are treated in accordance with the present invention, a selective sulphation at the hydroxy group occurs and the double bond remains unsulphated. Such products have special properties and characteristics which make them of great value in the textile industry.

The present invention is a particularly efficient and smooth method for sulphating unsaturated aliphatic alcohols. The'mildness of the reaction makes it applicable to very labile compounds which ordinarily undergo undesirable side reactions when treated with sulphating agents. It is also a very selective method of sulphating unsaturated aliphatic alcohols since it causes the reaction to take place at hydroxyl groups while leaving points of unsaturation in the molecule unsulphated. In spite of the mildness of the reaction 2 mages high yields and accordingly very pure products can be obtained.

Products manufactured in accordance with the present invention have improved properties as surface active agents over products which have been made by sulphating unsaturated alcohols with the ordinary sulphating agents that cause sulphation to take place at the double bond as well as at the hydroxyl group. Products produced in accordance with the present invention have improved solubility and a better physical appearance. The ester which is employed in the sulphation reaction need not be recovered but may be left in the product to which it will impart a pleasant odor.

The above description and example are intended to be illustrative only and not to limit the scope of the invention. Any departure therefrom which conforms to the spirit of the invention is intended to be included within the scope of the appended claims.

I claim: Y I

l. A method of sulphating an unsaturated primary aliphatic alcohol containing at least 8 carbon atoms which comprises reacting said alcohol with a strong sulphating agent in the presence of an alkyl ester of an aliphatic monocarboxylic acid containing from 1 to 8 carbon atoms wherein the alkyl group in said ester contains from 1 to 8 carbon atoms.

2. A method of preparing an unsaturated aliphatic sulphate containing at least 8 carbon atoms which comprises reacting an unsaturated primary aliphatic alcohol containing at least 8 carbon atoms with chlorosulphonic acid in the presence of an ester selected from the group consisting of the methyl, ethyl, and propyl esters of formic and acetic acids.

3. A method of preparing oleyl sulphate which comprises reacting oleyl alcohol with chlorosulphonic acid in the presence of ethyl acetate.

MAX ENGELMANN. 

